1. Field of the Invention
The disclosure relates to a low-dropout linear regulator (LDO), to a method for providing a low-dropout linear regulator (LDO) and to a method for operating a low-dropout linear regulator (LDO).
2. Background
For voltage regulators used in portable powered devices, it is desirable to provide a low output noise as well as a high Power Supply Rejection Ratio (PSRR) while powering sensitive analogue components, e.g. high-resolution analog digital converters (ADC), low-noise amplifiers, mixers, audio components or the like. For providing such low-noise supply voltages, low-dropout linear regulators (LDO) may be used.
Further, to minimize power dissipation, LDOs may be used in a post-regulation configuration cascaded with a DC/DC converter. Within such a configuration, the input of the LDO is connected to the noisy output of the DC/DC converter. Thus, the LDO may act as a post filter to supply the sensitive analogue components.
Actual demands on reducing coil size result in increasing switching frequency of the DC/DC converter. This leads to a need for the LDO to have a sufficiently high PSRR ratio also at higher frequencies of e.g. 100 kHz to 6 MHz.
Accordingly, it is an aspect of the present invention to provide a low-dropout linear regulator with an improved PSRR.